This invention relates generally to an engine and more particularly to a system for cooling intake air with the engine having an exhaust gas recirculation system.
The use of turbocharged engines is a common practice. The turbocharger increases the quantity of air for combustion and increases the heat value or temperature of the intake air. To compensate for the increased temperature of the intake air, an aftercooler is used to reduce the temperature of the compressed intake air. Many of the cooling systems include a water jacket aftercooler. In the water jacket aftercooler a coolant from the engine is circulated through the aftercooler and the intake air is cooled. The use of engine coolant limits the temperature to which the intake air can be cooled. More recently, the cooling medium of the aftercooler has been converted to use ambient air and an air to air aftercooler has replaced the water jacket aftercooler. As the emissions from engines become more strict, exhaust gas recirculation systems are used to reduce the emissions from such engines. Experience has shown that in some applications and under some operating conditions, especially when using high sulfur fuels, as the intake air is cooled water condenses from the air and with the addition of recirculated exhaust gas sulfuric acid is formed. As the intake air is circulated the sulfuric acid reduces the efficiency and longevity of the engine. Since ambient air is used as a donor intake air and the coolant or recipient fluid, the temperature and humidity of the ambient air varies depending on geographic location and season. Thus, the temperature and humidity of the intake air varies accordingly. Under these varying conditions the formation of water, resulting in sulfuric acid effects combustion and varying characteristics of combustion and the operation of the engine in a negative way. Under certain conditions the emissions therefrom can be increased and the structure of the engine can be damaged due to erosion. And, if the intake air is over cooled, excessive power can be developed and structural damage to the engine will occur. Thus, a system for controlling the temperature of the intake air is needed.
The present invention is directed to overcome one or more of the problems as set forth above.
In one aspect of the invention a system for controlling the temperature of an intake air flow used to support combustion in an engine is disclosed. The system has an exhaust gas having a portion thereof circulated to the intake air flow. An air to air aftercooler has the intake air flow being a donor fluid. An ambient air flow acts as a recipient fluid for cooling the intake air flow and passing through the aftercooler. A plurality of sensors are operatively positioned in the ambient air flow and the intake air flow. A controller is operative connected to the plurality of sensors. One of the ambient air flow restriction system has a restriction device and an intake air flow restriction system has a restriction device. And, the controller defines a position of the restriction device between an open position and a closed position.